battery fog.jpg

Work continues through the fog in installing rip-rap as a buffer along the High Battery at the tip of Charleston's peninsula on Wednesday, Jan. 2, 2019. Wade Spees/Staff

Some of the most publicized images from Tropical Storm Irma were the massive waves crashing over Charleston's High Battery.

Now the city has begun working on a fix: It's spending almost $1 million to replace about 7,800 tons of granite rock at the battery's base.

The work, which began late last month, will repair the iconic promenade from the largely unseen damage done during Irma in September 2017.

The storm's 10-foot tidal surge and wave action worked to strip away much of the existing stones, commonly known as riprap, that protect the High Battery's foundation, said Frank Newham, senior engineering project manager with the city's Public Service Department.

Hurricane Irma

Huge waves crash over the High Battery Monday, September 11, 2017, as the Charleston area was socked by Tropical Storm Irma. This year, the city is repairing damage to the rip rap at the battery's base. File/Brad Nettles/Staff

While Irma had been downgraded from hurricane to tropical storm status by the time it hit here, the storm still prompted a mass evacuation and its wind and waves brought severe flooding, spawned regional tornadoes and led to significant beach erosion and other damage. 

At the curve of the High Battery, which the city rebuilt about six years ago, roughly one-third to two-thirds of the stone apron was washed away, Newham said.

If the stones are not replaced, future storms and wave actions eventually would scour and undermine the battery's foundation, causing it to settle or fail.

The current work, being done by SJ Hamill Construction Co., will add a field of stones about 1,200 feet long, 2-2½ feet deep and about 40 feet wide from the curve to an outfall at Water Street, he said.

On Thursday morning about 20 people had gathered at low tide to watch a crew lift a small backhoe onto the newly created rocky shore.

Randy Lewis of Goose Creek was among them. He had driven by, seen the cranes and decided to return to see what was going on. "I'm very much intrigued," he said. "I love boats and barges and all that." 

Irma repair

Randy Lewis of Goose Creek joins more than a dozen other onlookers at Charleston's High Battery. They're watching a crew move a small backhoe into place to help add more rip rap to protect the battery's foundation. Jan. 3, 2019 Robert Behre/Staff

Newham said the Federal Emergency Management Agency will reimburse the city for 70 percent of the project's $935,000 price tag.

The riprap work is separate from the city's ongoing effort to raise its Low Battery, the lower part of the peninsula's seawall that runs from White Point Garden to the Coast Guard Station.

That project, estimated at about $60 million in total, is undergoing design and permitting work in conjunction with the Army Corps of Engineers and the state Department of Transportation.

Work on the first phase, the westernmost portion from Tradd Street to Ashley Avenue, is expected to cost about $9.5 million and would include road and utility work necessary to raise the wall there by 2½ feet. Construction could begin in several months.

"We hope to have the project out for bid by the end of February," Newham said. "But that is conditional on securing the permits."

Low battery

Water floods the Low Battery during Tropical Storm Irma on Sept. 11, 2017. The city is repairing storm damage to the High Battery, but it also soon plans to start work raising the Low Battery to help it protect from future flooding.  File/Matthew Fortner/Staff

In October, the Corps of Engineers announced it planned to spend $3 million on an in-depth study of the flood risks on the Charleston peninsula, a study that could lead to federal dollars for its future protection against rising seas and major storms.

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Reach Robert Behre at 843-937-5771. Follow him on Twitter @RobertFBehre.